I think that’s the intention; adding those 2 red hair colors solidly cement the fact that Void Elves come from Blood Elves. We can speculate that they will be inducting the Telogrus initiates, but those 2 red hair colors (+ the shared blonde one) to me are to represent that Blood Elves became the Void Elves.
(In the same manner, I do think that the two lightest hair colors are meant to represent High Elves, as they are their more recurring NPC hair colors)
Still I find it a very limiting hue choice, but I can see some logic behind it.
Agreed, should be divided out into two separate races, you can have some customization bleed over, but double down on the void theme for void elves and put the work into making a proper high elf race like should have been done. Same for Wildhammer and any other race that got lumped into the original instead of having the work done.